JP3281965B2 - Pneumatic booster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic booster mounted on a braking device of an automobile or the like, and more particularly to an improvement of a pneumatic booster using a negative pressure and a compressed air pressure as a boost source. is there.

[0002]

2. Description of the Related Art A pneumatic booster mounted on a braking device of an automobile or the like generally uses an intake negative pressure of an engine as a boosting source. In addition, some use compressed air pressure as a boost source. A conventional pneumatic booster using a negative pressure and a compressed air pressure as a boost source as described above is shown in FIGS.
This will be described next using FIG. The pneumatic booster shown in FIGS. 5 and 6 has been filed by the present applicant in Japanese Patent Application No. 5-257823, and the plunger provided in the valve body is reduced in diameter to reduce the size. It is designed to work.

As shown in FIGS. 5 and 6, in a pneumatic booster 1, a housing 2 is defined by a power piston 4 through a diaphragm 3 into a negative pressure chamber 5 and a variable pressure chamber 6. Further, a pressure accumulation chamber 7 is provided adjacent to the transformation chamber 6. The negative pressure chamber 5 is connected to a negative pressure source such as an intake device of the engine and is always in a negative pressure state, and the accumulator chamber 7 is connected to a compressed air source such as a compressor and is always in a pressurized state. Has become.

[0004] One end of a valve body 8 is connected to the power piston 4 and a cylindrical portion 9 formed on the other end of the valve body 8 extends through the accumulator chamber 7 in an airtight and slidable manner to the outside. Has been issued. On the side wall of the cylindrical portion 9, a negative pressure passage 10 communicating the inside thereof with the negative pressure chamber 5, a positive pressure passage 11 communicating with the variable pressure chamber 6, and a passage hole 12 communicating with the pressure accumulating chamber 7 are provided. ing. A substantially cylindrical retainer 13 is fitted in the cylindrical portion 9, and the snap ring 15 is fitted in the inner peripheral groove 14 of the cylindrical portion 9 so that the retainer 13 does not come off from the cylindrical portion 9. Fixed. The retainer 13 has a passage 16 that allows the passage hole 12 of the cylindrical portion 9 to communicate with the retainer 13, and a retainer 13.
An atmosphere passage 17 is provided for communicating the inside of the cylindrical portion 9 partitioned by 13 with the atmosphere side.

[0005] A plunger 18 is slidably fitted in the retainer 13. The plunger 18 is provided with a compressed air passage 19 having one end constantly communicating with the passage 16 of the retainer 13 and the other end opened into the cylindrical portion 9. An operating rod 20 is connected to one end of the plunger 18, and a push rod 21 connected to the valve body 8 is connected to the other end.
, Via a reaction disk 22 made of an elastic material. The operating rod 17 is connected to a brake pedal (not shown), and the tip of the push rod 21 is in contact with a piston (not shown) of the master cylinder.

An atmospheric pressure control valve is formed in the cylindrical portion 9 by a valve member 23 attached to the retainer 13, and the negative pressure passage 10 and the atmospheric passage 17 are selected by moving the plunger 18 with respect to the valve body 8. It can be opened and closed. Also, the valve member 24 attached to the plunger 18
Constitutes a compressed air pressure control valve, and the compressed air passage 19 and the atmospheric passage 17 can be selectively opened and closed by movement of the plunger 18 with respect to the valve body 8. In the figure, 25 and 26 are return springs, 2
7, 28 are valve springs. Here, when the pneumatic booster is not operating and the plunger 18 is in the retracted position, a slight gap is formed between the tip of the plunger 18 and the right end surface of the reaction disc 22. It has become.

Next, the operation of the pneumatic booster 1 will be described. Normally, the valve body 8 and the plunger 18 are in the retracted position shown in the figure by the return springs 25 and 26, the valve member 23 closes the atmosphere passage 17 and closes the negative pressure passage 10, and the valve member 24 closes the positive pressure passage 10. The compressed air passage 19 is closed by connecting the tube 11 to the cylindrical portion 9. Therefore, the variable pressure chamber 6 is communicated with the negative pressure chamber 5 through the positive pressure passage 11, the inside of the tubular portion 9, and the negative pressure passage 10, and has the same pressure as the negative pressure chamber 5.

When the plunger 18 is advanced through the gap formed between the plunger 18 and the right end surface of the reaction disk 22 by operating the brake pedal and operating the rod 20, the valve member 23 opens the air passage 17. As a result, the atmosphere is introduced into the variable pressure chamber 6 through the atmosphere passage 17, the cylindrical portion 9, and the positive pressure passage 11, and a pressure difference is generated between the negative pressure chamber 5 and the variable pressure chamber 6, and this pressure difference is generated. As a result, a thrust is generated in the power piston 4 to apply a servo force to the push rod 21.

When the operating force of the brake pedal is further increased, the plunger 18 advances further, and the valve member 24 cuts off the communication between the positive pressure passage 11 and the inside of the cylindrical portion 9 and at the same time, connects the compressed air passage 19 to the positive pressure passage 11. To communicate with As a result, the compressed air in the pressure accumulating chamber 7 is introduced into the variable pressure chamber 6 through the passage holes 12, the passage 16, the compressed air passage 19, and the positive pressure passage 11, and is interposed between the negative pressure chamber 5 and the variable pressure chamber 6. A large pressure difference is generated, and the thrust of the power piston 4 is increased by the pressure difference, so that a larger servo force is applied to the push rod 21.

When the operating force of the brake pedal is released, the plunger 18 returns to the retracted position by the elastic force of the return spring 25 and the reaction disk, and the variable pressure chamber 6 communicates with the negative pressure chamber 5. The thrust of the power piston 4 due to the pressure is eliminated, and the push rod 21 and the valve body 8 are returned by the return spring 26.
Is retracted, and the braking by the operation of the master cylinder is released.

As described above, by introducing the atmospheric pressure and the compressed air pressure into the variable pressure chamber 6 stepwise, a large servo force can be obtained and the servo force can be controlled smoothly.

[0012]

However, in the conventional pneumatic booster 1 described above, the snap ring 15 is engaged with the retainer 13 fitted in the tubular portion 9 to the inner peripheral groove 14 of the tubular portion 9. Since it is fixed so as not to come off from the tubular portion 9, it is necessary to form the inner peripheral groove 14 in the tubular portion 9, which requires much time and effort in manufacturing. Further, in order to fit the snap ring 15 into the inner peripheral groove 14 of the cylindrical portion 9, a special tool is required, and there is a problem that the assembling workability is poor. Further, the cylindrical portion 8
The strength of the valve body 8 is reduced because the inner circumferential groove 14 is formed at the bottom.

The present invention has been made in view of the above points, and does not require an inner circumferential groove and a snap ring of a cylindrical portion for preventing a retainer fitted to the cylindrical portion of a valve body from coming off. It is an object of the present invention to provide a pneumatic booster.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention defines a negative pressure chamber connected to a negative pressure source, a variable pressure chamber, and the negative pressure chamber and the variable pressure chamber. A power piston, a valve body connected to the power piston and having a cylindrical portion, a passage hole penetrating inside and outside of a side wall of the cylindrical portion, and an outside of the side wall being connected to a compressed air source; A cylindrical retainer having a passage fitted in the portion and communicating with the passage hole, and a plunger having a compressed air passage fitted slidably in the retainer and communicating the passage of the retainer in the cylindrical portion; A negative pressure passage, a positive pressure passage, and an atmospheric passage for communicating the inside of the cylindrical portion with the negative pressure chamber, the variable pressure chamber, and the atmosphere, and the compressed air passage, the negative pressure passage, and the positive pressure passage according to movement of the plunger. And a control valve for opening and closing each of the air passages A pneumatic booster for introducing air or compressed air into the transformation chamber according to the movement of the plunger and applying a servo force to a power piston by a pressure difference between the negative pressure chamber and the transformation chamber. At
A stopper protruding from the inner peripheral surface of the tubular portion and restricting the retainer from coming off the tubular portion is fitted into a passage hole provided in the tubular portion of the valve body.

[0015]

With this configuration, the retainer is prevented from falling out of the cylindrical portion by fitting the stopper into the passage hole in the side wall of the cylindrical portion and projecting the stopper from the inner peripheral surface of the cylindrical portion. Can be.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. The pneumatic booster of this embodiment is different from the conventional example shown in FIGS. 5 and 6 only in that the inner peripheral groove and the snap ring of the valve body are omitted and a stopper is added. Hereinafter, the same members as those in the above-described conventional example are denoted by the same reference numerals, and only different portions will be described in detail.

As shown in FIG. 1, the pneumatic booster of this embodiment has a substantially cylindrical retainer 13 fitted in a tubular portion 9 of a valve body 8 in the same manner as the above-mentioned conventional one. I have. A circumferential groove 12a is formed in the inner peripheral surface of the cylindrical portion 9 and penetrates the inside and outside of the side wall to open the inside into the groove 12a and communicate with the compressed air source through the pressure accumulating chamber 7 on the outside. A passage hole 12 having a rectangular cross section is provided. The retainer 13 has a circumferential outer circumferential groove 29 facing the passage hole 12 of the cylindrical portion 9.
The passage 16 is provided in the outer peripheral groove 29 and communicates with the passage hole 12 and the compressed air passage 19 of the plunger 18. Step formed on the outer periphery of one end of retainer 13
The valve member 23 is formed of the cylindrical member 9 and the step portion 31 formed on the inner peripheral surface of the cylindrical portion 9.
The valve member 23 is supported by sandwiching the base end 23a of
Further, a gap between the tubular portion 9 and the retainer 13 is sealed by the base end portion 23a. The other end of the retainer 13 and the cylindrical portion 9
Is sealed by an O-ring 32.

A stopper 33 is fitted into the passage hole 12 of the cylindrical portion 9, and the tip of the stopper 33 projects from the inner peripheral surface of the cylindrical portion 9 and engages with the outer peripheral groove 29 of the retainer 13. 13 is held so as not to come off from the tubular portion 9. As shown in FIGS. 2 and 3, the stopper 33 has a substantially arcuate shape that fits into an arc-shaped space formed by the passage hole 12 having a rectangular cross section provided on the side wall of the tubular portion 9, and has a longitudinal direction. A flexible claw portion 34 that expands outward is formed on the inner peripheral side of both ends. Then, as shown in FIG. 4, when the stopper 33 is fitted into the passage hole 12, the inner peripheral portion of the stopper 33 projects from the inner peripheral surface of the cylindrical portion 9 and the claw portion 34 becomes the edge of the passage hole 12. And the stopper is locked in the passage hole 12. Further, the inner peripheral portion of the stopper 33 protruding from the inner peripheral surface of the cylindrical portion 9 is engaged with the outer peripheral groove 29 of the retainer 13 to hold the retainer 13 so as not to come off from the cylindrical portion 9. . The stopper 33 has a passage 35 for connecting the pressure accumulating chamber 7 to the passage 16 of the retainer 13 along the passage hole 12 when the stopper 33 is fitted in the passage hole 12.
Is provided. The stopper 33 is made of claw 33
It is good to use an elastic body such as a synthetic resin so that is easily bent.

The operation of the embodiment constructed as described above will now be described. The stopper 33 is mounted by fitting the retainer 13 into the cylindrical portion 9 of the valve body 8 and then stopping the stopper 33.
33 is pushed into the passage hole 12 from the outside of the cylindrical portion 9 and the claw portion 34 is bent and inserted. When the stopper 33 is inserted to a predetermined position, the claw portion 34 is expanded and engaged with the edge of the passage hole 12 to be fixed. At this time, the inner peripheral portion of the stopper 33 projects from the inner peripheral surface of the cylindrical portion 9 and the retainer
The retainer 13 is engaged with the outer peripheral groove 29 of the cylindrical portion 9 so as not to fall out of the tubular portion 9.

As described above, the stopper 33 can hold the retainer 13 in the tubular portion 9 by being inserted into the passage hole 12 from the outside of the tubular portion 9 and can be easily assembled without special tools. be able to. Further, since the cylindrical portion 9 is not provided with an inner peripheral groove for attaching a snap ring, the strength of the valve body 8 is increased. In addition, stopper 33
Use the passage hole 12 as a through hole to fit
Since the pressure accumulating chamber 7 and the passage 16 of the retainer 13 are communicated by the passage 35 of the 33, there is no need to separately provide a through-hole in the side wall of the cylindrical portion for attaching the stopper 33.

In this embodiment, the stopper 33 is provided with a passage.
35, but instead of the passage 35, a recess extending from the outer peripheral side to the inner peripheral side of the stopper 33 is formed.
A passage may be formed between the side wall 12 and the pressure accumulation chamber 7 and the passage 16 of the retainer 13.

[0022]

As described above in detail, according to the pneumatic booster of the present invention, the stopper is fitted into the passage hole in the side wall of the cylindrical portion and is projected from the inner peripheral surface of the cylindrical portion. In addition, the retainer can be prevented from coming off from the cylindrical portion. As a result, the stopper can be easily assembled without special tools, and since there is no inner circumferential groove for attaching the snap ring to the cylindrical part, the strength of the valve body is increased and productivity is improved. An excellent effect is achieved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of an embodiment of the present invention.

FIG. 2 is a plan view of a stopper of the device of FIG. 1;

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is an enlarged view showing a state in which a stopper is fitted in a passage hole of a cylindrical portion in the apparatus of FIG. 1;

FIG. 5 is a longitudinal sectional view of a conventional pneumatic booster.

6 is a longitudinal sectional view of a main part of the device of FIG.

[Explanation of symbols]

 Reference Signs List 4 Power piston 5 Negative pressure chamber 6 Variable pressure chamber 7 Accumulation chamber 8 Valve body 9 Cylindrical part 10 Negative pressure passage 11 Positive pressure passage 12 Passage hole 16 Passage 17 Atmospheric passage 18 Plunger 19 Compressed air passage 23,24 Valve member (control valve) ) 33 Stopper

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-89429 (JP, A) JP-A-7-89431 (JP, A) JP-A-7-69207 (JP, A) (58) Field (Int. Cl. ⁷ , DB name) B60T 13/57

Claims (1)

(57) [Claims] 1. A valve body having a negative pressure chamber connected to a negative pressure source, a variable pressure chamber, a power piston defining the negative pressure chamber and the variable pressure chamber, and a cylindrical portion connected to the power piston. And a passage hole that penetrates the inside and outside of the side wall of the cylindrical portion, and the outside of the side wall is connected to a compressed air source, and a passage that is fitted in the cylindrical portion and communicates with the passage hole. A retainer, a plunger fitted slidably in the retainer and having a compressed air passage communicating the passage of the retainer into the cylindrical portion, and a inside of the cylindrical portion into each of the negative pressure chamber, the transformation chamber and the atmosphere. A plunger comprising: a negative pressure passage, a positive pressure passage, and an atmospheric passage to be communicated with each other; and a control valve that opens and closes each of the compressed air passage, the negative pressure passage, the positive pressure passage, and the atmospheric passage according to movement of the plunger. Air in the transformer chamber according to the movement of Or a pneumatic booster that introduces compressed air to apply a servo force to the power piston by a pressure difference between the negative pressure chamber and the variable pressure chamber,
An air pressure, wherein a stopper that protrudes from an inner peripheral surface of the cylindrical portion and regulates the retainer from coming off from the cylindrical portion is fitted into a passage hole provided in the cylindrical portion of the valve body. Type booster.